Scratch Building Tires - Diamond Tread Cutting

[brahman104]

Good topic you've started here Jay, some excellent responses here and an excellent mix of old and new technologies; Paul going the old school way and Peter with no small amount of technical wizardry. I think both methods are equally valid and I have a long way to go to be good at either, but what these two gentlemen have done is shown that it CAN be done

 

Thanks for your contributions Gents!

 

Craig

[dodgem37]

'Diamond treads with a helical offset, and winding up (ho ho) back at block one with precision and no overlap are a whole other ballgame.

Obviously, the tyre making companies managed it full-size 60 years ago without CADCAM, but that's not what we're talking about.

 

It can probably be done by hand - eventually, after all errors have been minimized one unit at a time by a 'traditional' modelmaker - but really?

Out in hobbyland?

C'mon...'

Now you're just talking to hear your own voice.

 

Sincerely,

Mark

Edited June 5, 2016 by dodgem37

[Zero77]

I have no mini lathe or milling machine. I wish I did.

I bought a bunch of kit wheels and tires from ebay years ago. They included 1/24, 1/25 car tires. Plus all the ones I tossed in my scrap piles over the years after I bought resin replacements.

If I need diamond treads, I try to find the actual tire sizes, convert it to 1/32 scale and hunt for one in my junk box that is close to actual in scale. I can adjust the width if needed then cast a copy in resin. If it has a diamond tread, or something that resembles it, I will use it as a guide. If not, I will use the two part epoxy and lay a thin layer all around the tire. I smooth it and blend it into the sidewalls as much as possible with a wet finger or cotton swab. Sometimes I will wait for a few hours for it to harden slightly then with the back of an x-acto blade I will very, very slowly and carefully roll a pattern starting on the "bottom", the flat I sanded into the resin tire. It takes several, or in some cases many tries before I get it close enough. Then I let it harden fully and sand around the tread to thin it down and give the pattern a sharper edge.  Most of the time I have clean up the grooves and sand some more. The one in the photo still needs the treads sanded.

 

 

 

This is true craftmanship !

[Chek]

'Diamond treads with a helical offset, and winding up (ho ho) back at block one with precision and no overlap are a whole other ballgame.

Obviously, the tyre making companies managed it full-size 60 years ago without CADCAM, but that's not what we're talking about.

 

Now you're just talking to hear your own voice.

Sincerely,

Mark

 

I'm not sure what point you're making Mark - a fault in my terminology maybe?

 

What I was trying to get across was that making diamond treads would be similar to that of making helical gears

 

with a second offset pass slanted in the opposite direction to form the tread elements.

 

No offence intended to any engineers present.

[dodgem37]

'Diamond treads with a helical offset . . . and no overlap are a whole other ballgame.

It is a simple diagonal grid pattern.

 

'Obviously, the tyre making companies managed it full-size 60 years ago without CADCAM, but that's not what we're talking about.'

If we're not talking about making a grid pattern without CAD then what are we talking about?  The initial question is how to make a diamond pattern without CAD:

Can anyone describe to me how one would cut WW2-style diamond treads instead of block treads?  I know it can be done, but I just cannot figure out how, outside of just plain brute force hand whittling, which will not give the needed accuracy plus would be soul-crushing difficult.

 

It can probably be done by hand - eventually, after all errors have been minimized one unit at a time by a 'traditional' modelmaker - but really?'

Scratch builders do not ask themselves, 'Why?'  They ask themselves, 'How?'

 

Off of the top of my head, to solve the problem Jay proposes; measure the circumference of the tire, use tape.  Lay the tape flat, and measure.  That is the length.  Measure the pattern width, again use tape.  Measure the tape.  Now you have the rectangle into which you can draw the diagonal grid.

 

Draw a center-line down the length of the rectangle.  Draw a center-line thru the width of the rectangle.  Divide both length and width as required.  Draft diagonal grid.  

 

Once you find the sweet number of diamond patterns to fit the space you need to transfer that to the tire.  Draw your length-wise center-line on the tire.  Draw a diagonal line on a piece of tape.  Cut tape the width of the diamond.  Align the diagonal line on the tape with length-wise line on the tire.  Draw your diagonal.  Repeat as required.  

 

Incise the lines.

 

Others mileage may vary.

Sincerely,

Mark

 

 

 

 

 

[Guest Paul Budzik]

This thread is a perfect example of what happens with limited experience in solving issues.  It's like going to school ... yes you learn a few things, but what you really learn is how to learn.  The more you create, the more you learn how.  Exactly why I started my video series and titled it "Outside the Box.

 

So as a hint to solving this ... think indexing heads and jigs.  So many issues are solved with first making a jig.

 

And to cool your brain, here is some more old school modeling ...

 

https://www.youtube.com/channel/UCrdcVbQE5fUvTKxMbhnN_KQ

 

Paul

[Out2gtcha]

I would LOVE to learn more about CAD/CAM stuff,and how to use programs like Rhino. I have learned a lot of modeling techniques over the years, and experimented and failed with a lot too.

 

The CAD programs, along with an ever growing and advancing number of 3D printers suited to home printing.......and an ever shrinking price point, I think will be the next thing I want to add to my personal modeling Rolodex of techniques. I think there are SO many possibilities for this it's insane.

[JayW]

Hi Paul - and hi modelers who are contributing to this thread. I didn't know there was this much interest.

 

Paul is the only guy I know of who has created a diamond pattern on a model tire from scratch apparently without the use of 3D computer modeling technology. Paul, I have seen your articles on the P-51 and P-47, now and quite a while back when I was building the 1/18 P-38 wheels. And those patterns are precisely what I am talking about. However the articles give no hints at how it was done. The hint you have provided:

 

"think indexing heads and jigs. So many issues are solved with first making a jig."

 

did not give me an aha moment! Give me another hint! Save me from scribing grooves for my next project!

[airscale]

I would LOVE to learn more about CAD/CAM stuff,and how to use programs like Rhino. I have learned a lot of modeling techniques over the years, and experimented and failed with a lot too.

 

The CAD programs, along with an ever growing and advancing number of 3D printers suited to home printing.......and an ever shrinking price point, I think will be the next thing I want to add to my personal modeling Rolodex of techniques. I think there are SO many possibilities for this it's insane.

 

 

Thats the spirit Brian - I just got a 90 day free trial for Rhini and watched some youtube videos to get started (it is well served..) - it costs NOTHING to have a go. It is mainly a matter of adding or taking away shapes I find. I know Tim did a tutorial, I might do one on making wheels as if you have a go these are really straightforward to start with making use of some simple but useful features

 

It doesn't mean you are not creative, lack experience solving problems or lose traditional skills, it does mean you have a new and very flexible weapon in your armoury for making things that are very difficult to get right where a high degree of symetery or repetition are involved. I can't afford the big cost of a full licence so just bunch up the work I need for a project into the 90 day trial window

 

try it..

 

Peter

[JayW]

BTW Airscale - adding diamonds rather than cutting grooves. Why didn't I think of that? However I am not sure I can get good accuracy. I will be thinking on that - thanks! Wish Paul would just tell us....

 

Paul - when I first saw pictures of your P-38 a couple years ago I honestly thought it might be the actual aircraft - it is that convincing. I commend you on that effort. It was an inspiration for me to go after that 21CT monster of mine. But, I am off topic. It did however convince me that the block tread is a good alternative.

[GrahamF]

Actually I've done this with my CNC setup but the way I do it is a combination of 3D machining and 2.5D machining. The tyre shape is machined with a ball end cutter but the score lines are grooved by 'dropping' a 2D cutting path onto the 3D shape using an engraving cutter. This ensures that the grooves are sharp. Whilst I could CAD up in Rhino all the detail of the grooves you are then restricted to using a 3D style cutter (ball end)of a small diameter.

Graham

[Out2gtcha]

It doesn't mean you are not creative, lack experience solving problems or lose traditional skills, it does mean you have a new and very flexible weapon in your armoury for making things that are very difficult to get right where a high degree of symetery or repetition are involved.

 

 

BINGO

[Bill_S]

Pick a gear, any gear. The number of teeth on the gear is the number of diamonds down the center of the tire.

 

I like jigs and fixtures.

 

A pin holds the gear (and tire) stationary. The outer cylinder rotates to set angle(s), and locks down with a set screw. The slit is for a modeling saw. Once a groove is cut, pull the gear locking pin, and advance the gear by a tooth.

[JayW]

Bill!!!!  What a great idea!  Something akin to that has to be the way.  Will be putting some major thought to that.

[D.B. Andrus]

http://www.geocities.jp/yoyuso/p40/p40e.html

 

Scroll down to "Details".

 

HTH,

 

D.B.